Cardiotomy reservoirs are currently used in major surgical procedures, such as open heart surgery, for receiving blood from a cardiotomy sucker and other sources, for defoaming the blood, filtering out debris and returning it to the patient.
Numerous designs of cardiotomy reservoirs are commercially offered, for example, a cardiotomy reservoir similar to that disclosed in U.S. Pat. No. 3,993,461, and its predecessor in design being as disclosed in U.S. Pat. No. 3,891,416. In both of these cardiotomy reservoirs, a hollow casing is provided in which a tubular member is positioned within the casing and extends between the ends thereof. Blood enters the bottom of the tubular member, rising upwardly until it passes out of an aperture to the exterior of the tubular member.
The Shiley cardiotomy reservoir which is currently commercially available also comprises a casing having a tubular member extending through the interior from end to end, with filter and defoaming material carried outside of the tubular member. Blood enters the top of the reservoir through inlet ports at a side thereof, then normally falling downwardly and then passing through the defoaming material within the casing from where it is returned to the patient. The space within the tubular member is not used.
The lower end of the tubular member of the Shiley reservoir is retained by a bottom hump, in the lower end of the casing. The periphery of the lower end is sloped slightly to allow blood to flow to the lowest point, where the outlet is positioned.
One problem with this reservoir and its side entry blood inlet ports is that some blood coming in one port can swing around the circumference of the tubular casing and flow out one of the other ports, rather than falling downwardly into the defoaming material.
In introducing blood to a cardiotomy reservoir, it is also highly desirable to avoid the harsh impingement of blood upon a wall surface or the like, since that can result in an increase in the hemolysis level of the blood. On the other hand, blood which is introduced into one of the entry ports of a cardiotomy reservoir should not have the tendency to squirt out of the other entry ports. Furthermore, the reservoir should have a configuration that prevents the trapping of air pockets during use. Likewise, it is desirable to be able to provide calibration of the amount of blood in the reservoir, down to volumes as low as 25 or 50 cc..
The above and other advantages are provided in the cardiotomy reservoir of this invention, for improved processing of blood with reduced hemolysis.